The molecular basis of intracellular iron metabolism rests with the regulation of expression and assembly of ferritin. In order to understand the detailed mechanisms of this regulation we have cloned the entire functional gene for the heavy (H) chain of human ferritin. This gene has been fully characterized and has been introduced into mouse cells in order to dissect the genetic elements responsible for its regulated expression. In addition cross reacting sequences located near the HLA locus of chromosome 6 have been identified and are currently being cloned. This may provide a link to the genetic basis of hereditary hemochromatosis.